1. Field of the Invention
The present invention relates generally to satellite-type printing press for sheet-fed printing, or more precisely, to sheet perfecting apparatus for such printing press.
2. Description of the Prior Art
Satellite-type printing press is known in which many printing units (four color units, for example) are provided in satellite-like manner around common pressure cylinder of large diameter. Such satellite-type printing press is a new step toward corresponding to the need of multi-sort short run printing.
In Japanese unexamined patent laid-open 244195/1996, a technique is disclosed in which a plurality of satellite-type printing presses are connected via sheet perfecting apparatus. According to the technique, four color printing is done on the surface of sheet by first satellite-type press and, after reversing the sheet, also four color printing is put on the opposite side of the sheet by the second satellite-type press.
From Japanese unexamined patent laid-open 169645/1987, for example, a technique is well known in which many printing units are connected in series and sheet perfecting apparatus is interposed therein.
It is true that both sides of sheet can be printed at one pass by the satellite-type printing press shown in before-mentioned Japanese unexamined patent laid-open 244195/1996, but the equipment is huge and switching of printing format is not at all flexible, as the technique presupposes two satellite-type printing units.
Also, before-mentioned sheet perfecting apparatus of series type printing press has a tendency to cause register error through gripping change of sheet, as the perfecting apparatus stays the sheet transfer path during one-side printing in which sheet perfecting is not needed.
In view of the above-described problems of the prior art techniques, the present invention provides an improved sheet perfecting apparatus for satellite-type printing press and aims at enabling double-side printing by only one satellite-type printing press itself, and preventing register error without connecting with sheet transfer path in case sheet reversing is not needed.
In accordance with sheet perfecting apparatus of the present invention, in the course of many printing units which are provided in satellite-like manner around a common pressure cylinder, a plurality of chain gripper means are paralleled and these means are connected via a perfecting cylinder.
The first chain gripper means accept the front end of sheet from common pressure cylinder and the sheet is then turned toward distant direction of common pressure cylinder. In the course of such sheet transfer, the rear end of sheet is gripped by perfecting gripper of perfecting cylinder and the sheet is reversed in accordance with the rotation of the cylinder. Then, the sheet is approached and transferred from the second chain gripper means to common pressure cylinder.
These and other objects of the invention will become apparent from the following description with reference to the drawings. But, these show merely an embodiment of the present invention.